Thermosensitive radiator caps



July 31, 1962 J. E. ESHBAUGH ETA. 3,047,235

THERMOSENSITIVE RADIATOR CAPs Filed April 15, 1959 @nite tates @arent has 3,047,235 THERMOSENSlTIVE RADIATOR CAPS .lesse E. Eshbangh and .lohn A. McDougal, Flint, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Apr. 15, 1959, Ser. No. 506,549 4 Claims. (Cl. 236-92) rlfhis invention relates to radiator caps and more particularly 'to radiator caps for pressurized engine cooling systems as utilized on automobile Vehicles.

In order to prevent loss of engine coolant it is conventional to place engine cooling systems under pressure with provisions being made in the radiator filler caps for venting the systems when the coolant pressure is either too high or too low. Operating an engine under elevated but controlled coolant pressure conditions insures heat transfer efciency, reduces the -size of cool-ant system necessary and conserves coolant.

A conventional type radiator cap comprising a pressure relief valve and a vacuum relief valve 'is disclosed in the U.S. Patent No, 2,266,314 granted December 16, 1941, in the name of I. E. Eshbaugh. In such a cap, both valves are normally closed. It has been found that in 4caps of this type, as employed in cooling systems of internal combustion engines, the starting of a cold engine is soon followed by an expansion of the coolant and a consequent decrease in the air space of the radiator. This causes a rise of pressure long before the coolant boiling temperature is attained and this rise would occur during many short cold weather motor trips. This situation definitely increases radiator fatigue and sho-rtens the life expectancy of the radiator.

It has now been found that `the number of pressure cycles to which `a radiator is subjected may be reduced -appreciably and that the life of a radiator may therefore be extended with retention of the advantages of a pressurized system.

To this end, an object of the present invention is to provide an improved pressure type radiator cap which will remain vented during periods of engine warm-up and thereby minimizel the number of pressure cycles to which a radiator and cooling system are subjected.

A feature of the present invention is a radiator cap having a therrnostatic unit Amounted outside the vapor or steam space. Another feature is a radiator cap with Xa thermal element loosely attached to a vacuum relief valve, the weight of the latter tending to open the valve.

'llnese :and other important features of the invention will now be described in detail in the specification and then pointed out more particularly inthe appended claims.

yIn the drawings:

FIGURE 1 is a sectional view in elev-ation of a radiator filler spout vassembly with a pressure type radiator cap thereon as an illustration of one embodiment of the present invention;

FIGURE 2 is a sectional view looking in the direction of the arrows 2-2 in FIGURE 1 showing `a portion of the construction;

FIGURE 3 is an enlarged view of la portion of the structure shown in FIGURE 1, a vacuum relief valve being shown in its closed position; and

. FGURE 4 is a side elevation of a portion of the filler spout of FIGURE 1, the cap Ibeing shown in dot and dash lines. Y

In FIGURE 1, a head tank portion of a radiator is shown to which is fixed a tubular liller spout 12 with an overflow or vent pipe 14 leading from the side wall of the spout to -a point of discharge as is conventional. The lower end of the spout l2 has yan inturned flange including an upwardly directed annular rib or valve seat 16. The lower end of the spout terminates in a depending annular skirt Ztl which extendsinto `an opening 22 of the top wall of the radiator 1t). The upper end of the spout 12 is flanged outwardly to form an annular rib 24 and a pair of dependen-t arcuate flanges 26 which are adapted to serve as elements of a conventional and detachable bayonet connection. These flanges 'are adapted to cooperate with a pair of inturned flanges 28 integral with the bot- Itom edge of an inverted cap member generally indicated at 30.

A resilient metallic sealing `disk 3-2 is provided forming a seal with the annular rib 24. The disk 32 is fixed at its center :to the center of the cap 30 by a depending stud 34 which is riveted in position. A` valve seating spring 36 surrounds the post 34 and the upper end of the spring seats against the underside of the diaphragm 32. At the opposite end of the spring 36 is located an annular shoulder 3S of a valve element 40. The latter has a central dome 42 which is lslidably mounted on the post 34 and is provided with primary vent openings 44. The lower end of the post S4 is provided with a shoulder 46 limi-ting the downward movement of the dome member from the stud when the cap is removed from the radiator lil. On its underside the valve element 40 carries a sealing gasket 4S which is adapted 'to seat on the annular rib 22. A cup-like closure member 50 is press fitted within the valve member 4G and a closure wall 52 is integral therewith. This wall bears -at least one secondary vent opening 54 which is within a circle defined by a downwardly extending rib 56 formed on the wall. A relief valve 60 is adapted to seat on .the rib 56 or on the underside of the wall 52 to seal the vent opening or openings 54. This relief or secondary Valve 60 includes a stud 62 which is slidable through the Wall 52 and is fixed at its bottom end to a rigid disk 64. A vsealing disk 66 is conned between the disk 64 `and a shoulder 68 formed on the stud 62. The upper end of the stud 62 is provided with an annular shoulder 70 in contact witha thermostatic element 72. The latter is formed of three pieces of dierent metal making its deflection dependent upon temperature and is in the shape of a beam extending across a depressed area of the vented wall 52.

Much of the cap structure is like that described in the Patent No. 2,266,314, -above referred to, but the relief valve of FlGURE 3 involves the present invention and it is to the latter structure as used in la radiator cap that the description herein is primarily limited.

lIt will be noted that the stud 62 is slidable through the wall 52. When the parts are positioned as shown in FIGURE 1, the valve 60 is open and the radiator head tank 10 is vented to the atmosphere by way of the overllow tube 14. Upon starting la cold engine, however, a rush of vapor through the Vent openings 54 is not sufhcient to lift the relief valve 60 to its closed position until the thermostatic element 72 has been affected by a sucient elevated temperature to supplement the action of the vapor. When the thermostatic element 72 -and the rush of vapor act in concert, the valve 60 will rise and they system will become pressurized with the valve 60 closed as shown in FIG. 3. If the valve 60 relied on weight alone to hold it open and on the flow of vapor alone to cause it to close, then a high rate of vapor rilow would be' required to close the valve and this would entail considerable loss of coolant and anti-freeze before the valve 6i) would close. The thermostatic element 72 may be so calibrated that the valve 60 will close before -a great rush of vapor could occur `during an engine warm-up period and for this reason less coolant loss results. the thermostatic valve 6G is `adjusted to close at 160 F. and -the coolant cools below 212, it would be possible' to have a slight sub-atmospheric pressure in the radiator 10. The strength. of the thermostatic element 72, however, should be no greater than the normal Vacuum relief valve spring conventionally used and for this reason no greater vacuum could build up with the thermostatic element than is conventional.

It is obvious that the thermostatic element 72 could be made of two or three metals or could be such as to have more than two diverging branches. It will be noted that only a single beam with two ends are shown in FIGURE 2 as simplicity of structure dictates such a beam intermediately pierced by the stud 62. Itis necessary that adequate clearance be left between the wall 52 and the thermostatic element 72 to delay pressure build-up by proper venting when the valve 60 is unseated from the ridge 56 or positioned as shown in FIGURE 1.

We claim:

1. A radiator cap of the pressurized type and attachable to a radiator filler spout, said cap having fixed parts including a vented valve element and a closure wall traversing said valve element and having a vent opening therein, a stud vertically slidable in saidwall, a valve member carried by said stud beneath said wall, said valve member being vertically movable to seat on said wall around said opening, a thermostatic member immediately above said wall land supporting said stud on said :fixed parts, and the arrangement being such that a rise in temperature plus the effect o f vapor flow through said opening cooperates to effect flexure of the thermostatic member and seating of the valve member around said opening.

2. A radiator cap attachable to the ller spout of a radiator and having iixed parts including a closure wall within the cap having a vent opening therein and annular sealing means surrounding said wall, a headed stud slidable through said Wall, a valve member carried by the lower end of said stud and facing the underside of said wall, said stud and valve member comprising an assembly of solid elements vertically movable to seat said valve member on said wall to close said Vent opening when said assembly is subjected to a given temperature, and a thermostatic member directly above said wall operatively connected to said stud and supporting said valve member f in spaced relation to said wall at a lower temperature.

3. A radiator cap attachable to the ller spout of a radiator and including a closure wall having a vent opening therein, a `stud slidable in said Wall, a valve member carried by the end of said stud on one side of said wall for controlling said vent opening, a thermosensitive member on the other side of said wall with opposite ends only resting on said Wall thereby supporting said stud and valve member and bridging said vent opening, said stud, valve member and thermosensitive member forming la solid assembly movable with respect to said wall, and said thermosensitive member being adapted to hold said valve member in aclosed position with respect to said vent opening at normal operating temperature and to suspend said valve 4member away from said closed position at a lower temperature.

4. A radiator cap comprising .a valve element carrying annular sealing means adapted to engage a valve seat within a tubular ller spout serving a radiator, a primary vent opening in said valve element, a wall fixed to said valve element and traversing a space dened by said sealing means and communicating'with said primary vent, a secondary vent opening in said wall, a stud slidable through said wall, a valve member and a thermostatic member connected to said stud, said valve member being movable with said stud to seat on one side of said wall and close said secondary vent opening, and said thermostatic member being arranged between said primary vent opening and the other side of said Wall whereby a rise in tempera-ture plus the effect of vapor flow through said secondary opening on said valve member may effect seating of the latter.

References Cited inthe tile of this patent UNITED STATES PATENTS 442,911 Poulson Dec. 16, 1890 1,712,257 Coleman May 7, 1929 1,813,122 Moore July 7, 1931 2,396,400 Vitagliano Mar. 12, 1946 2,480,986 Walker Sept, 6, 1949 2,535,974 Watkins Dec. 26, 1950 2,764,353 Lavallee Sept. 25, 1956 

